Michael Pitts,Michael Pitts / Engine room ventilator shafts of oil tanker 'Seiko Maru'. Sunk in Chuuk Lagoon 17/18th February 1944, Chuuk Lagoon, Pacific

Michael Pitts,Michael Pitts / Divers on the wreck of the tugboat, 'Tienstin'. Abu Galawa, Red Sea, July 2010

Juergen Freund / Crinoids or featherstars covering a coral bommie with dive boat looming overhead, West New Britain, Papua New Guinea

Juergen Freund / Split level of dive boat "Seven Seas", coral reef and island, Komodo NP, Indonesia, August 2009.

Juergen Freund / Member of West Papuan dive boat crew free-swimming underwater. North Raja Ampat, West Papua, Indonesia, February 2010

Flip Nicklin / Southern Right Whale (Eubalaena australis) researchers Roger Payne, right, Jim Darling, left, and Gustavo Alvarez Colombo, center, watching individual dive, Peninsula Valdez, Argentina

Alex Mustard / Split level photograph of a liveaboard dive boat (M.Y. Whirlwind), anchored near a coral reef, at sunet. Ras Katy, Sharm El Sheikh, Sinai, Egypt. Red Sea

Mark Carwardine / Humpback whale (Megaptera novaeangliae) tail fluke above water about to dive with whale watching boat behind, Bay of Fundy, New Brunswick, Canada

Franco Banfi / Scouting the river on a small boat driven by an electric motor ready to dive, Formoso River, Bonito, Mato Grosso do Sul, Brazil

Magnus Lundgren / Wild Wonders of China / A dive boat in Sai Kung archipelago, Hong Kong, China. June, 2016.

Linda Pitkin / Dive boats moored at beach, Triton Bay, near Kaimana, West Papua, Indonesia, March 2017

David Fleetham / Bugis schooner, live-aboard dive vessel, at anchor in a limestone island lagoon, Uranie Island, Raja Ampat, West Papua, Indonesia.